In collaboration with the CDC and participating cities, the San Francisco Department of Public Health (SFDPH) proposes to monitor HIV prevalence, incidence, related risk behavior and utilization of prevention services among men who have sex with men [unreadable] (MSM), injection drug users (IDU) and heterosexuals living in high-risk areas (HET) through time location sampling (TLS) and respondent driven sampling (RDS) surveys via a yearly cycle. Methods are based on those established by the CDC and field tested in San Francisco during the initial round of NHBS. We envision that the surveys will continue the surveillance activities initiated by NHBS whereby changes in HIV incidence and related risk behavior will be detected through successive waves of a minimum of 500 subjects per risk population per wave. Data will also be used to plan prevention and care programs and evaluate the community-level impact of prevention efforts over time. The surveys will help assess our progress towards the goal of reducing new HIV infections by 50% by 2010. [unreadable] [unreadable] [unreadable]